scholarly journals Brain oscillations track the formation of episodic memories in the real world

2016 ◽  
Author(s):  
Benjamin Griffiths ◽  
Ali Mazaheri ◽  
Stefan Debener ◽  
Simon Hanslmayr
Keyword(s):  
Episodic Memory ◽  
Real World ◽  
Medial Temporal Lobe ◽  
Spatial Clustering ◽  
Inferior Frontal Gyrus ◽  
Low Frequency ◽  
Blind Spot ◽  
Memory Formation ◽  
The Real ◽  
Beta Power

Despite the well-known influence of environmental context on episodic memory, little has been done to enhance contextual richness within the lab. This leaves a blind spot lingering over the neuronal correlates of episodic memory formation in the real world. To address this, we presented participants with series of words to memorise along a pre-designated route across campus. Meanwhile, a mobile EEG system acquired the associated neural activity. Replicating lab-based subsequent memory effects (SMEs), we identified significant low-frequency power decreases, including beta power decreases over the left inferior frontal gyrus. Additionally, the paradigm enabled us to dissociate the oscillatory correlates of temporal and spatial clustering. Specifically, we found spatially clustered items exhibited significantly greater theta power decreases within the left medial temporal lobe than temporally clustered items. These findings go beyond lab-based studies, which are limited in their capabilities to investigate environmental contextual factors that guide memory formation.

scholarly journals Alpha/beta power decreases during episodic memory formation predict the magnitude of alpha/beta power decreases during subsequent retrieval

2021 ◽  
Vol 153 ◽  
pp. 107755
Author(s):  
Benjamin J. Griffiths ◽  
María Carmen Martín-Buro ◽  
Bernhard P. Staresina ◽  
Simon Hanslmayr ◽  
Tobias Staudigl
Keyword(s):  
Episodic Memory ◽  
Memory Formation ◽  
Beta Power ◽  
Alpha Beta

scholarly journals On the Effectiveness of Event-related Beta tACS on Episodic Memory Formation and Motor Cortex Excitability

2016 ◽  
Author(s):  
Verena Braun ◽  
Rodika Sokoliuk ◽  
Simon Hanslmayr
Keyword(s):  
Motor Cortex ◽  
Episodic Memory ◽  
Inferior Frontal Gyrus ◽  
Memory Formation ◽  
Frequency Range ◽  
Beta Oscillations ◽  
Healthy Human ◽  
Sham Stimulation ◽  
Motor Cortex Excitability ◽  
Beta Frequency

AbstractBackgroundTranscranial alternating current stimulation (tACS) is widely used to entrain or modulate brain oscillations in order to investigate causal relationships between oscillations and cognition.ObjectiveIn a series of experiments we here addressed the question of whether event-related, transient tACS in the beta frequency range can be used to entrain beta oscillations in two different domains: episodic memory formation and motor cortex excitability.MethodsIn experiments 1 and 2, 72 healthy human participants engaged in an incidental encoding task of verbal and non-verbal material while receiving tACS to the left and right inferior frontal gyrus (IFG) at 6.8Hz, 10.7Hz, 18.5Hz, 30Hz, 48Hz and sham stimulation for 2s during stimulus presentation.In experiment 3, tACS was administered to M1 at the individual motor beta frequency of eight subjects. We investigated the relationship between the size of TMS induced MEPs and tACS phase.ResultsBeta tACS did not affect memory performance compared to sham stimulation in experiments 1 and 2. Likewise, in experiment 3, MEP size was not modulated by the tACS phase.ConclusionsOur findings suggest that event-related, transient tACS in the beta frequency range cannot be used to modulate the formation of episodic memories or motor cortex excitability. These null-results question the effectiveness of event-related tACS to entrain beta oscillations and modulate cognition.

scholarly journals Predictive entrainment of natural speech through two fronto-motor top-down channels

2018 ◽  
Author(s):  
Hyojin Park ◽  
Gregor Thut ◽  
Joachim Gross
Keyword(s):  
Inferior Frontal Gyrus ◽  
Low Frequency ◽  
Precentral Gyrus ◽  
Top Down ◽  
Low Frequencies ◽  
Left Inferior Frontal Gyrus ◽  
Delta Phase ◽  
Beta Power ◽  
Intelligible Speech ◽  
Spatio Temporal

AbstractNatural communication between interlocutors is enabled by the ability to predict upcoming speech in a given context. Previously we showed that these predictions rely on a fronto-motor top-down control of low-frequency oscillations in auditory-temporal brain areas that track intelligible speech. However, a comprehensive spatio-temporal characterisation of this effect is still missing. Here, we applied transfer entropy to source-localised MEG data during continuous speech perception. First, at low frequencies (1-4 Hz, brain delta phase to speech delta phase), predictive effects start in left fronto-motor regions and progress to right temporal regions. Second, at higher frequencies (14-18 Hz, brain beta power to speech delta phase), predictive patterns show a transition from left inferior frontal gyrus via left precentral gyrus to left primary auditory areas. Our results suggest a progression of prediction processes from higher-order to early sensory areas in at least two different frequency channels.

scholarly journals Intracranial Recordings and Computational Modeling of Music Reveal the Time Course of Prediction Error Signaling in Frontal and Temporal Cortices

2019 ◽  
Vol 31 (6) ◽  
pp. 855-873 ◽  
Author(s):  
Diana Omigie ◽  
Marcus Pearce ◽  
Katia Lehongre ◽  
Dominique Hasboun ◽  
Vincent Navarro ◽  
...  
Keyword(s):  
Prediction Error ◽  
Time Course ◽  
Inferior Frontal Gyrus ◽  
Low Frequency ◽  
Anterior Cingulate ◽  
Predictive Processing ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Middle Temporal Gyrus ◽  
Beta Power

Prediction is held to be a fundamental process underpinning perception, action, and cognition. To examine the time course of prediction error signaling, we recorded intracranial EEG activity from nine presurgical epileptic patients while they listened to melodies whose information theoretical predictability had been characterized using a computational model. We examined oscillatory activity in the superior temporal gyrus (STG), the middle temporal gyrus (MTG), and the pars orbitalis of the inferior frontal gyrus, lateral cortical areas previously implicated in auditory predictive processing. We also examined activity in anterior cingulate gyrus (ACG), insula, and amygdala to determine whether signatures of prediction error signaling may also be observable in these subcortical areas. Our results demonstrate that the information content (a measure of unexpectedness) of musical notes modulates the amplitude of low-frequency oscillatory activity (theta to beta power) in bilateral STG and right MTG from within 100 and 200 msec of note onset, respectively. Our results also show this cortical activity to be accompanied by low-frequency oscillatory modulation in ACG and insula—areas previously associated with mediating physiological arousal. Finally, we showed that modulation of low-frequency activity is followed by that of high-frequency (gamma) power from approximately 200 msec in the STG, between 300 and 400 msec in the left insula, and between 400 and 500 msec in the ACG. We discuss these results with respect to models of neural processing that emphasize gamma activity as an index of prediction error signaling and highlight the usefulness of musical stimuli in revealing the wide-reaching neural consequences of predictive processing.

Semantic memory before episodic memory: How memory research can inform knowledge and belief representations

2021 ◽  
Vol 44 ◽  
Author(s):  
R. Shayna Rosenbaum ◽  
Julia G. Halilova ◽  
Thanujeni Pathman
Keyword(s):  
Episodic Memory ◽  
Semantic Memory ◽  
Real World ◽  
Developmental Studies ◽  
Belief Attribution ◽  
Memory Research ◽  
Memory Theory ◽  
The Real

Abstract Knowledge and belief attribution are discussed in the context of episodic and semantic memory theory and research, with reference to patient-lesion and developmental studies under naturalistic conditions. Consideration of how episodic and semantic memory relate to each other and intersect in the real world, including how they fail, can illuminate the approach to studying how people represent others' minds.

scholarly journals Overcoming Blind Spots in the Real World: Leveraging Complementary Abilities for Joint Execution

2019 ◽  
Vol 33 ◽  
pp. 6137-6145
Author(s):  
Ramya Ramakrishnan ◽  
Ece Kamar ◽  
Besmira Nushi ◽  
Debadeepta Dey ◽  
Julie Shah ◽  
...  
Keyword(s):  
Real World ◽  
Cost Effective ◽  
Blind Spot ◽  
Imitation Learning ◽  
Second Step ◽  
The Real ◽  
Open World ◽  
Hand Off ◽  
Noisy Labels ◽  
Blind Spots

Simulators are being increasingly used to train agents before deploying them in real-world environments. While training in simulation provides a cost-effective way to learn, poorly modeled aspects of the simulator can lead to costly mistakes, or blind spots. While humans can help guide an agent towards identifying these error regions, humans themselves have blind spots and noise in execution. We study how learning about blind spots of both can be used to manage hand-off decisions when humans and agents jointly act in the real-world in which neither of them are trained or evaluated fully. The formulation assumes that agent blind spots result from representational limitations in the simulation world, which leads the agent to ignore important features that are relevant for acting in the open world. Our approach for blind spot discovery combines experiences collected in simulation with limited human demonstrations. The first step applies imitation learning to demonstration data to identify important features that the human is using but that the agent is missing. The second step uses noisy labels extracted from action mismatches between the agent and the human across simulation and demonstration data to train blind spot models. We show through experiments on two domains that our approach is able to learn a succinct representation that accurately captures blind spot regions and avoids dangerous errors in the real world through transfer of control between the agent and the human.

scholarly journals Directional coupling of slow and fast hippocampal gamma with neocortical alpha/beta oscillations in human episodic memory

2019 ◽  
Vol 116 (43) ◽  
pp. 21834-21842 ◽  
Author(s):  
Benjamin J. Griffiths ◽  
George Parish ◽  
Frederic Roux ◽  
Sebastian Michelmann ◽  
Mircea van der Plas ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Memory Retrieval ◽  
Memory Formation ◽  
Beta Power ◽  
Wide Range ◽  
Alpha Beta ◽  
Episodic Memories ◽  
Hippocampal Theta ◽  
Multisensory Information ◽  
Flow Of Information

Episodic memories hinge upon our ability to process a wide range of multisensory information and bind this information into a coherent, memorable representation. On a neural level, these 2 processes are thought to be supported by neocortical alpha/beta desynchronization and hippocampal theta/gamma synchronization, respectively. Intuitively, these 2 processes should couple to successfully create and retrieve episodic memories, yet this hypothesis has not been tested empirically. We address this by analyzing human intracranial electroencephalogram data recorded during 2 associative memory tasks. We find that neocortical alpha/beta (8 to 20 Hz) power decreases reliably precede and predict hippocampal “fast” gamma (60 to 80 Hz) power increases during episodic memory formation; during episodic memory retrieval, however, hippocampal “slow” gamma (40 to 50 Hz) power increases reliably precede and predict later neocortical alpha/beta power decreases. We speculate that this coupling reflects the flow of information from the neocortex to the hippocampus during memory formation, and hippocampal pattern completion inducing information reinstatement in the neocortex during memory retrieval.

scholarly journals Disentangling the roles of neocortical alpha/beta and hippocampal theta/gamma oscillations in human episodic memory formation

2020 ◽  
Author(s):  
Benjamin J. Griffiths ◽  
María Carmen Martín-Buro ◽  
Bernhard P. Staresina ◽  
Simon Hanslmayr
Keyword(s):  
Episodic Memory ◽  
Memory Performance ◽  
Empirical Support ◽  
Memory Formation ◽  
Information Representation ◽  
Gamma Phase ◽  
Beta Power ◽  
Alpha Beta ◽  
Phase Amplitude ◽  
Hippocampal Theta

AbstractEpisodic memory formation relies on at least two distinct capabilities: 1) our ability to process a vast amount of sensory information, and 2) our ability to bind these sensory representations together to form a coherent memory. The first process is thought to rely on a reduction in neocortical alpha/beta power, while the second is thought to be supported by hippocampal theta-gamma phase-amplitude coupling. However, most studies investigating human episodic memory use paradigms where the two cognitive capabilities overlap. As such, empirical support for the distinction of the two associated neural phenomena is lacking. Here, we addressed this by asking seventeen human participants (11 female, 6 male) to complete a sequence-learning paradigm that temporally separated information representation from mnemonic binding, while MEG recordings were acquired. We found that a decrease in neocortical alpha/beta power during the perception of the sequence correlated with enhanced memory performance. Similar power decreases during mnemonic binding, however, had no bearing on memory formation. In contrast, an increase in hippocampal theta/gamma phase-amplitude coupling during mnemonic binding correlated with enhanced memory performance, but similar coupling during sequence perception bared no relation to later memory performance. These results demonstrate that alpha/beta power decreases and hippocampal theta/gamma phase-amplitude coupling represent two temporally dissociable processes in episodic memory, with the former relating to information representation while the latter relates to mnemonic binding.

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